阅读说明：本技术 一种基于射频mems开关的t型可调滤波器 (T-shaped adjustable filter based on radio frequency MEMS switch ) 是由 吴倩楠 韩路路 李孟委 王姗姗 范丽娜 于 2020-05-09 设计创作，主要内容包括：本发明属于可调滤波器技术领域,具体涉及一种基于MEMS开关的T型可调滤波器,包括衬底,所述衬底上固定有两个镜像设置的T型可调谐振器,所述衬底上设有输入谐振器及输出谐振器。所述T型可调谐振器是由弯折T型谐振器、多个射频MEMS开关和多个接地端子组成,所述T型谐振器的尾部弯折,从而缩短整体尺寸。T型谐振器的头部左右两侧分别设有射频MEMS开关,所述射频MEMS开关另一端分别与接地端子相连,接地端子通过TSV通孔与背面接地层相连。本发明可减小滤波器尺寸,降低系统复杂度,具有体积小、高Q值、低损耗、高带外抑制、易集成等优点。在0.01-22GHz的范围内,有着优越的实用性,实现了MEMS开关与微带线结构的高度集成。本发明用于不同频率的滤波。(The invention belongs to the technical field of tunable filters, and particularly relates to a T-shaped tunable filter based on an MEMS switch. The T-shaped adjustable resonator is composed of a bent T-shaped resonator, a plurality of radio frequency MEMS switches and a plurality of grounding terminals, and the tail of the T-shaped resonator is bent, so that the overall size is shortened. The left side and the right side of the head of the T-shaped resonator are respectively provided with a radio frequency MEMS switch, the other end of each radio frequency MEMS switch is connected with a grounding terminal, and the grounding terminal is connected with a back grounding layer through a TSV through hole. The invention can reduce the size of the filter, reduce the complexity of the system, and has the advantages of small volume, high Q value, low loss, high out-of-band rejection, easy integration and the like. The high-precision MEMS switch has excellent practicability in the range of 0.01-22GHz, and realizes high integration of the MEMS switch and the microstrip line structure. The invention is used for filtering different frequencies.)

1. A T-shaped tunable filter based on a radio frequency MEMS switch is characterized in that: the circuit comprises a substrate (1), a ground layer (7) arranged on the back surface of the substrate (1), an input resonator (3-1) and an output resonator (3-2) arranged on the front surface of the substrate (1), and a resonator group arranged between the input resonator (3-2) and the output resonator (3-2);

the input resonator (3-1) and the output resonator (3-2) are both composed of a linear transmission line (3-3), an L type high-impedance transmission line (3-4) and a first grounding terminal (5), the linear transmission line (3-3) is connected with a L type high-impedance transmission line (3-4), and the L type high-impedance transmission line (3-4) is connected with the first grounding terminal (5) in a capacitive coupling mode;

the resonator group comprises two T-shaped tunable resonators arranged in a mirror image mode, each T-shaped tunable resonator comprises a T-shaped resonator (4), a plurality of radio frequency MEMS switches (2) and a plurality of second grounding terminals (6), at least two radio frequency MEMS switches (2) are arranged, the number of the second grounding terminals (6) is the same as that of the radio frequency MEMS switches (2), and the T-shaped resonators (4) are respectively connected with the corresponding second grounding terminals (6) through the radio frequency MEMS switches (2);

the first ground terminal (5) and the second ground terminal (6) are connected with a ground layer (7) on the back surface of the substrate (1) through TSV through holes (8).

2. The T-type tunable filter based on the radio frequency MEMS switch as claimed in claim 1, wherein: one end of the T-shaped resonator (4) far away from the radio frequency MEMS switch (2) is of a bent structure, and one end of the T-shaped resonator (4) far away from the radio frequency MEMS switch (2) is connected with a grounding layer (7) on the back of the substrate (1) through a TSV through hole (8).

3. The T-type tunable filter based on the radio frequency MEMS switch as claimed in claim 1, wherein: the radio frequency MEMS switch (2) comprises an anchor point (2-1), a contact (2-2) and a cantilever beam (2-3), one end of the cantilever beam (2-3) is fixed on a second grounding terminal (6) through the anchor point (2-1), the contact (2-2) is fixed on a T-shaped resonator (4), and the other end of the cantilever beam (2-3) is suspended right above the contact (2-2).

4. The T-type tunable filter based on the radio frequency MEMS switch as claimed in claim 3, wherein: and a driving electrode (2-4) is arranged right below the cantilever beam (2-3), the driving electrode (2-4) is connected with a driving lead (2-7), and one surface of the driving electrode (2-4) facing the cantilever beam (2-3) is provided with a dielectric layer (2-5).

5. The T-type tunable filter based on the radio frequency MEMS switch as claimed in claim 3, wherein: the cantilever bridge (2-3) is provided with an array of release holes (2-6), the array of release holes (2-6) is arranged in 1-8 rows and 1-10 columns, the diameter of each release hole (2-6) is 8-15 mu m, and the distance between every two adjacent release holes (2-6) is 15-25 mu m.

6. The T-type tunable filter based on the radio frequency MEMS switch as claimed in claim 4, wherein: the dielectric layers (2-5) are made of silicon nitride or hafnium oxide.

7. The T-type tunable filter based on the radio frequency MEMS switch as claimed in claim 1, wherein: the diameter of the TSV through hole (8) is 100-400 mu m.

Technical Field

The invention belongs to the technical field of tunable filters, and particularly relates to a T-shaped tunable filter based on a radio frequency MEMS switch.

Background

Band-pass filters are a class of important electronic components that allow signals in a particular frequency band to pass through, and play a significant role in wireless communication systems and test equipment. With the development of modern communication technology, in the face of the increasing requirements of high integration, miniaturization, multi-function multiplexing and reconfigurability in the design of communication systems, the traditional single-frequency filter cannot fully meet the requirements. Tunable filter design has become one of the research hotspots in recent years because the use of tunable filters can not only greatly reduce the size and complexity of the system, but also can meet the multiplexing requirements of multiple communication protocols.

At present, the national mechanisms for researching the adjustable filter mainly comprise a microelectronic research institute of the Chinese academy of sciences, a Nanjing electronics research institute, a Mi-electric fifty-four institute, a Nanjing university of science and technology, a Wuhan university, a Zhongbei university, a limited responsibility company of the four-Sichuan nine-continent electrical appliance group, and the like. For example, Nanjing university of technology has designed a high-performance tunable filter (application number: 201610530252.4) based on a zero-order resonator, which includes two port feeders, two blocking capacitors, a zero-order resonant unit, and a varactor diode, and the center frequency of the filter is adjusted by changing the capacitance of the varactor diode. A finite responsible company of the electrical appliance group of Jiuzhou Sichuan designs a stripline tunable filter (application number: 201320179424. X), which comprises a power supply control part and a stripline tunable filter cavity, wherein the stripline tunable filter wall comprises: rectangular metal resonance pole and high Q value varactor. The adjustable frequency band is changed by controlling the variable capacitance diode, so that the adjustable frequency band is realized. However, the two tunable filters have the problems of complex structure, poor out-of-band rejection, large volume, difficult integration and the like.

Disclosure of Invention

Aiming at the technical problems of complex structure, poor out-of-band rejection, large volume and difficult integration of the tunable filter, the invention provides the T-shaped tunable filter based on the radio frequency MEMS switch, which has compact structure, high Q value, low insertion loss and high out-of-band rejection.

In order to solve the technical problems, the invention adopts the technical scheme that:

a T-shaped tunable filter based on a radio frequency MEMS switch comprises a substrate, a ground layer arranged on the back surface of the substrate, an input resonator and an output resonator which are arranged on the front surface of the substrate, and a resonator group arranged between the input resonator and the output resonator;

the input resonator and the output resonator are respectively composed of a linear transmission line, an L type high-impedance transmission line and a first grounding terminal, the linear transmission line is connected with the L type high-impedance transmission line, and the L type high-impedance transmission line is connected with the first grounding terminal in a capacitive coupling mode;

the resonator group comprises two T-shaped tunable resonators arranged in a mirror image mode, each T-shaped tunable resonator comprises at least two T-shaped resonators, a plurality of radio frequency MEMS switches and a plurality of second grounding terminals, the number of the second grounding terminals is the same as that of the radio frequency MEMS switches, and the T-shaped resonators are connected through the second grounding terminals corresponding to the radio frequency MEMS switches respectively;

and the first ground terminal and the second ground terminal are connected with the ground layer on the back surface of the substrate through the TSV.

And one end of the T-shaped resonator, which is far away from the radio frequency MEMS switch, is connected with the ground layer on the back surface of the substrate through the TSV through hole.

The radio frequency MEMS switch comprises an anchor point, a contact and a cantilever beam, wherein one end of the cantilever beam is fixed on the second grounding terminal through the anchor point, the contact is fixed on the T-shaped resonator, and the other end of the cantilever beam is suspended right above the contact.

And a driving electrode is arranged under the cantilever beam, the driving electrode is connected with a driving lead, and one surface of the driving electrode facing the cantilever beam is provided with a dielectric layer.

The cantilever bridge is provided with a release hole array which is 1-8 rows and 1-10 columns, the diameter of each release hole is 8-15 mu m, and the distance between every two adjacent release holes is 15-25 mu m.

The dielectric layer is made of silicon nitride or hafnium oxide.

The diameter of the TSV through hole is 100-400 mu m.

Compared with the prior art, the invention has the following beneficial effects:

compared with the traditional band-pass filters such as the traditional ferrite tunable filter, the cavity tunable filter, the semiconductor tunable filter, the ferroelectric tunable filter and the like, the invention can reduce the size of the whole system, reduce the switching power consumption and the complexity of the system, and has the advantages of compact structure, high Q value, low insertion loss, high out-of-band rejection and the like. In the range of 0.01-22GHz, the filter has excellent band-pass filtering characteristic. The invention can be tuned by changing the electrical length of the resonator by the gating state of the switch. In addition, the invention reduces the use number of the radio frequency MEMS switches, thereby greatly prolonging the service life of the tunable filter. Therefore, the invention realizes the tuning with multiple working frequencies and high performance of 0.01-22 GHz.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is another schematic structural view of the present invention;

FIG. 3 is a schematic diagram of the structure of the RF MEMS switch of the present invention;

FIG. 4 is a schematic structural diagram of the cantilever bridge of the present invention;

FIG. 5 is a simulation of the S-parameters of the tunable filter of the present invention;

the MEMS switch comprises a substrate 1, a radio frequency MEMS switch 2, an anchor point 2-1, a contact 2-2, a cantilever beam 2-3, a driving electrode 2-4, a dielectric layer 2-5, a release hole 2-6, a driving lead 2-7, an input resonator 3-1, an output resonator 3-2, a linear transmission line 3-3, a high-impedance transmission line L, a T-shaped resonator 4, a first grounding terminal 5, a second grounding terminal 6, a grounding layer 7 and a TSV through hole 8.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

A T-type adjustable filter based on radio frequency MEMS switches is disclosed, as shown in FIG. 1 and FIG. 2, the T-type adjustable filter comprises a substrate 1, a grounding layer 7 arranged on the back surface of the substrate 1, an input resonator 3-1 and an output resonator 3-2 arranged on the front surface of the substrate 1, and a resonator group arranged between the input resonator 3-2 and the output resonator 3-2, wherein the input resonator 3-1 and the output resonator 3-2 are both formed by a linear transmission line 3-3, a L type high-impedance transmission line 3-4 and a first grounding terminal 5, the linear transmission line 3-3 is connected with a L type high-impedance transmission line 3-4, the L type high-impedance transmission line 3-4 is connected with the first grounding terminal 5 in a capacitive coupling manner, the resonator group comprises two T-type adjustable resonators arranged in a mirror image manner, the T-type adjustable resonators comprise T-type resonators 4, a plurality of radio frequency MEMS switches 2 and a plurality of second grounding terminals 6, at least two radio frequency MEMS switches 2 are arranged, the number of the second grounding terminals 6 is the T-type resonators 4 are respectively connected with the corresponding second grounding terminals 6 through the plurality of radio frequency switches 2, and the T-type tunable filter is connected with the grounding layer 7 through four TSV switches 8, and the back surface of the TSV filter is controlled by the TSV filter.

Furthermore, one end of the T-shaped resonator 4, which is far away from the radio frequency MEMS switch 2, adopts a bending structure, so that the whole size is shortened. And one end of the T-shaped resonator 4 far away from the radio frequency MEMS switch 2 is connected with a ground layer 7 on the back surface of the substrate 1 through a TSV through hole 8. The electric length of the T-shaped resonator is changed by controlling the gating state of the radio frequency MEMS switch 2, so that the frequency is adjustable.

Further, as shown in fig. 3, the radio frequency MEMS switch 2 includes an anchor point 2-1, a contact 2-2, and a cantilever beam 2-3, wherein one end of the cantilever beam 2-3 is fixed to the second ground terminal 6 through the anchor point 2-1, the contact 2-2 is fixed to the T-type resonator 4, and the other end of the cantilever beam 2-3 is suspended over the contact 2-2.

Furthermore, a driving electrode 2-4 is arranged right below the cantilever beam 2-3, the driving electrode 2-4 is connected with a driving lead 2-7, and one surface of the driving electrode 2-4 facing the cantilever beam 2-3 is provided with a dielectric layer 2-5. The driving electrode 2-4 applies driving voltage through the driving lead 2-7, when the driving electrode 2-4 does not apply the driving voltage, the driving electrode 2-4 does not act, the cantilever beam 2-3 is separated from the contact 2-2, and the switch is in an off state. When the driving voltage acts on the driving electrode 2-4, the driving electrode 2-4 acts to generate electrostatic force to enable the cantilever beam 2-3 to deform, so that the cantilever beam is in contact with the electrode contact point 2-2, and the switch is in an on state.

Further, as shown in FIG. 4, the cantilever bridge 2-3 is provided with an array of release holes 2-6, preferably, the array of release holes 2-6 is provided in 1-8 rows and 1-10 columns, the diameter of the release hole 2-6 is 8-15 μm, and the distance between two adjacent release holes 2-6 is 15-25 μm.

Further, preferably, the dielectric layer 2-5 is made of silicon nitride or hafnium oxide, which has a high relative dielectric constant, so as to ensure the isolation between the cantilever beam 2-3 and the driving electrode 2-4.

Further, it is preferable that the diameter of the TSV 8 is 100-400 μm.

The working process of the invention is as follows: the driving electrode applies driving voltage through the driving lead, when the driving voltage is not applied to the driving electrode, the driving electrode does not act, the cantilever beam is separated from the contact, and the switch is in an off state. When the driving voltage acts on the driving electrode, the driving electrode acts to generate electrostatic force to enable the cantilever beam to deform, so that the cantilever beam is in contact with the electrode contact point, the switch is in an on state, and the adjustment of the working frequency of the T-shaped filter is achieved by controlling the gating states of the four radio frequency MEMS switches.